Pressure relief vent valve for a fluid tight sealed container especially an alkaline galvanic cell

ABSTRACT

A pressure relief vent valve for a fluid-tight sealed container and especially a sealed alkaline galvanic cell, the pressure relief vent valve comprising a resilient deformable ball of an elastomeric material which is positioned to overlie a vent orifice provided within the container and a retainer means for maintaining the ball in place over the vent orifice and in contact with a valve seat provided around the peripheral edge portions of the vent orifice and for compressing and deforming the ball into a flattened configuration forming a normally fluidtight seal between the ball and the valve seat.

United States Patent Amthor [541 PRESSURE RELIEF VENT VALVE FOR A FLUIDTIGHT SEALED CONTAINER ESPECIALLY AN ALKALINE GALVANIC CELL [72]Inventor: Helrnut K. Amthor, Rocky River, Ohio [73] Assignee: UnionCarbide Corporation, New York,

[22] Filed: Aug. 27, 1969 [2]] Appl. No.: 853,279

[52] US. Cl ..l36/178 [51] Int. Cl. ..I-l01m 1/06 [58] Field ofSearch..l36/l78, 177, 179, 180,169; 137/525; 220/44 [56] References CitedUNITED STATES PATENTS 2,182,266 12/1939 Schwartz ..l36/l78 2,306,98212/1942 Rolph ..l36/l78 2,321,089 6/1943 Keller ..l36/l78 51 May 23,1972 Primary Examiner-Anthony Skapars I Attorney-J. F. Hohmann and J. R.Doherty [5 7] ABSTRACT A pressure relief vent valve for a fluid-tightsealed container and especially a sealed alkaline galvanic cell, thepressure relief vent valve comprising a resilient deformable ball of anelastomeric material which is positioned to overlie a vent orificeprovided within the container and a retainer means for maintaining theball in place over the vent orifice and in contact with a valve seatprovided around the peripheral edge portions of the vent orifice and forcompressing and deforming the ball into a flattened configurationforming a normally fluid-tight seal between the ball and the valve seat.

19 Claims, 7 Drawing Figures Patented May 23, 1972 3,664,878

4 Sheets-Sheet 1 INVENTOR He/ f K. Amfhor Patented May 23, 1972 4Sheets-Sheet 2 la 23 I4 3 5 FIG. 4.

INVENTOR He/ f K. Amflror Pntented May 23, 1972 4 SheetsSheet 4 M pm (31INVENTOR Helm K. Amfhor PRESSURE RELIEF VENT VALVE FOR A FLUID TIGHTSEALED CONTAINER ESPECIALLY AN ALKALINE GALVANIC CELL This inventionrelates to a pressure relief vent valve useful for relieving highinternal gas pressures from inside a fiuid tight sealedcontainer. Morespecifically, the invention relates to improvements in resealablepressure relief vent valves provided in sealed alkaline galvanic cellsfor preventing the buildup of high internal gas pressures inside thecell container.

Alkaline galvanic cells may generate large quantities of gas undercertain conditions during use. Since these cells are required to befluid-tightly sealed at all times in order to prevent loss ofelectrolyte by leakage or evaporation, high internal gas pressures maydevelop. Such pressures may cause leakage, bulging or possible explosionof the cell if not properly vented. Especially in the case of secondaryor rechargeable cells, the vent must be resealable in order to avoiddrying out of the electrolyte over the normally long life of the cellsand to prevent ingress of oxygen and carbon dioxide.

In the past, several different types of resealable pressure relief ventvalves have been used for releasing high internal gas pressures frominside a sealed alkaline galvanic cell. One type of valve that has beencommonly used consists basically of a valve member such as a flat rubbergasket which is biased into sealing position over a vent orifice bymeans of a resilient member such as a helical spring. The resilientmember or spring is set to yield at a certain predetermined internal gaspressure momentarily breaking the seal and allowing the gas to escapethrough the vent orifice.

Another type of resealable pressure relief vent valve that has beentried is that disclosed and claimed in U.S. Pat. No. 3,293,081 issued to.l. L. S. Daley on Dec. 20, 1966. This resealable vent valve basicallyincludes an annular seal gasket such as an O-ring which is maintained insealing position around the periphery of the vent orifice by means of anarcshaped resilient member or spring. The resilient member or spring isset to yield and permit radial movement of the seal gasket momentarilybreaking the seal and allowing the passage of gas through the ventorifice when a predetermined high internal gas pressure is reachedinside the cell.

A major problem encountered with resealable pressure relief vent valvesof the type just described is that they are bulky and consequentlydifficult to incorporate into the cell assembly. Furthermore, thesepressure relief vent valves are expensive to manufacture and are not atall adaptable for incorporation into miniature size cells.

It is the primary object of this invention to provide a novel andimproved pressure relief vent valve for use in relieving high internalgas pressures from inside a fluid-tight sealed container and especiallyan alkaline galvanic cell.

It is another object of this invention to provide a novel and improvedpressure relief vent valve for an alkaline galvanic cell whichautomatically opens upon the build-up of a predetermined high internalgas pressure inside the cell and then reseal once the pressure has beenrelieved.

More specifically, another object of this invention is to provide anovel and improved resealable pressure relief vent valve for an alkalinegalvanic cell which is simple and compact and employs a minimum numberof parts, which is reliable and which can be so assembled as to beresponsive to a given gas pressure over a wide range of pressures, whichis inexpensive to manufacture and which can be easily adapted toincorporation within nearly all sizes of cells including miniature sizecells.

Broadly, the above and other related objects of this invention areachieved by a novel and improved pressure relief vent valve forrelieving high internal gas pressures from inside a fluid-tight sealedcontainer and especially a sealed alkaline galvanic cell, the pressurerelief vent valve comprising a resilient deformable ball of a suitableelastomeric material which is positioned to overlie a vent orificeprovided within the container. A retainer means is positioned over theresilient ball for maintaining the ball in place over the vent orificeand in contact with a valve seat provided around the peripheral edgeportions of the vent orifice and for compressing and deforming theresilient ball into a flattened configuration forming a normallyfluid-tight seal between the flattened ball and the valve seat. Theresilient ball is capable of undergoing further temporary deformationupon the build-up of a predetermined high internal gas pressure insidethe container momentarily breaking the seal and allowing gas to escapethrough the vent orifice.

According to a preferred feature of the invention, an alkaline galvaniccell incorporates a so-called two-mode" version of the pressure reliefvent valve wherein the resilient deformable ball of elastomeric materialis positioned within a deep vent orifice by forcing or pressing the ballthrough the opening of the vent orifice and exerts an initial highsealing force against the side walls of the vent orifice, sealing offthe passageway through the vent orifice from inside the cell. The ventvalve will remain closed with the resilient ball positioned within thevent orifice until the ball is expelled from the vent orifice by thebuildup of an abnormally high internal gas pressure inside the cell. Theresilient ball upon being expelled from the vent orifice allows some ofthe gas to escape from inside the cell but is thereafter caused to seatover the opening of the vent orifice by the retainer means in the samemanner as previously described, i.e., the ball is retained in aflattened configuration overlying the vent orifice so as to form anormally fluid-tight seal between the ball and the valve seat.

The preferred two-mode version of the pressure relief vent valve of theinvention is advantageous in that the valve can be set duringmanufacture of the cell to initially vent in its first mode of operationat a substantially higher pressure than the relatively low pressures atwhich the valve is operable in its second mode to vent and release gaspressure during normal use of the cell. During storage of the cell, thepressure relief vent valve will not open and vent until an abnormallyhigh internal gas pressure is developed and thus the cell is protectedagainst loss of moisture or water vapor which can result in drying outof the cell.

In the accompanying drawings:

FIG. 1 is an elevational, partially sectioned view of a typical alkalinegalvanic cell incorporating the pressure relief vent valve of theinvention;

FIG. 2 is an enlarged sectional view of the upper portion of the cellshown in FIG. 1;

FIG. 3 is an enlarged sectional view of the lower bottom portion of thecell shown in FIG. I and illustrates a different embodiment of theinvention;

FIG. 4'is a similar view illustrating another embodiment of theinvention;

FIG. 5 is a sectional view of the upper portion of a miniature size cellillustrating still another embodiment of the invention;

FIG. 6 is a sectional view of the upper portion of a similar cellillustrating still another embodiment of the invention; and

FIG. 7 is a sectional view of the lower portion of a cell similar tothat shown in FIG. 1 and illustrating a further embodiment of theinvention.

Referring now to the drawings in detail, there is shown in FIGS. 1 and 2a typical alkaline galvanic cell incorporating a pressure relief ventvalve in accordance with the invention. The cell comprises an invertedmetallic cupped container 10 provided with an outer metallic jacket 11separated from the container 10 by an insulating liner l2 suitably ofpaper or other fibrous material. Disposed within the container 10 is atubular anode l4 and a tubular cathode l5 and an alkaline electrolyte 16suitably an aqueous solution of potassium or sodium hydroxide. Thecathode 15 is juxtaposed in contact with the side walls of the container10 but is separated from the anode 14 by a liquid and gas permeable,electrolyte-containing separator medium 18. The separator medium 18 maybe composed of two juxtaposed layers of separator material placedbetween the anode l4 and cathode l5 and underlying the upper closed endof the container 10.

Suitably, the cell closure for this cell is of the type disclosed andclaimed in US. Pat. No. 3,042,734 issued to J. L. S. Daley on Feb. 15,1960. Such a cell closure comprises a generally U- shaped annular sealgasket for sealing the open end of the polarized cupped container 10, anunpolarized rigid metallic cover 21 which resides within the U-shapedannular seal gasket 20 and an oppositely polarized, centrally locatedterminal rivet 22 which is in contact with an anode current collector23. The seal gasket 20 is preferably made of a relatively hardnon-cold-flowable plastic material such as nylon and is radiallycompressed between the terminal rivet 22 and the metallic cover 21 andbetween the cover 21 and the lower peripheral edges of the container 10,thereby resulting in an extremely leak resistant fluid-tight sealedcell.

A metallic top cover plate 24 is provided for the cell and is formedwith a central protuberance 25 serving as the positive terminal of thecell. The top cover plate 24 is provided with a vent hole 26 and is alsoformed with a peripheral ring portion 27 which is fitted tightly aroundthe upper peripheral edges of the container 10 and is compressed orsqueezed radially inwardly to provide a smooth juncture between the ringportion 27 and the side walls of the container 10. The metallic jacket12 is locked in place around the upper and lower extremities of the cellby crimping its upper peripheral edges around the outer edges of the topcover plate 24 and by crimping its lower edges around the outer edges ofa metallic bottom plate 28. The bottom plate 28 is maintained inelectrical contact with the terminal rivet 22 and serves as the negativeterminal of the cell.

The preferred two-mode version of the pressure relief vent valve used inthe cell of FIGS. 1 and 2 includes a resilient ball 30 force-fitted orpressed into a smaller size circular vent orifice 32 formed within theupper closed end of the container 10. The resilient ball 30 is of aninitial spherical shape but is compressed and deformed into an elongatedor cylindrospherical configuration when force-fitted or pressed into thevent orifice 32. The vent orifice 32 is positioned to reside justbeneath the central protuberance 25 provided on the top cover plate 24and is formed with upwardly extending cylindrical side walls of asufficient depth to provide a fairly deep hole to contain the elongatedball 30. It will be seen that the ball 30 is placed under resilientstress when force-fitted or pressed into the vent orifice 32 and exertsan initial high sealing force against the side walls of the vent orifice32, sealing offthe passageway through the vent orifice 32.

During the period that the cell is placed on storage, the pressurerelief vent valve will remain sealed with the resilient elongated ball30 positioned within the vent orifice 32 until the ball 30 is expelledfrom the vent orifice 32 by the build-up of an abnormally high internalgas pressure inside the cell. The top over plate 24 and the centralprotuberance 25 are so designed that the space or gap between the bottomwall portion of the protuberance 25 and the upper peripheral edges ofthe vent orifice 32 is less than the diameter of the resilient ball 30in its initial spherical shape prior to being force-fitted or pressedinto the vent orifice 32. Thus, it will be seen that the ball 30 whenexpelled from the vent orifice 32 immediately comes into contact withthe flat bottom wall portion of the protuberance 25 which acts as aretainer means for the ball 30 and is compressed and deformed into aflattened configuration but in this instance the ball 30 is in aposition overlying the vent orifice 32 as shown in phantom lines inFIGS. 1 and 2. The resilient ball 30 upon first being expelled from thevent orifice 32 is compressed and deformed to such an extent by theabnormally high internal gas pressure inside the cell that the ball 30does not immediately seat with the peripheral edge portions of the ventorifice 32 providing an open passageway around the ball 30 for ventinggas from inside the cell. The gas follows a path through the ventorifice 32 around the ball 30 and out through the vent hole 26 providedin the top cover plate 24.

Once the initial abnormally high internal gas pressure has beenrelieved, the resilient stress exerted by the flattened ball 30 forcesthe ball 30 into a normally fluid-tight seal engagement around theperipheral edge portions of the vent orifice 32 forming a valve seat.The vent valve will remain closed sealing off the vent orifice 32 untilthe internal gas pressure during use or discharge of the cell builds upto some predetermined value which is less than the abnormally highpressure at which the resilient ball 30 is expelled from the ventorifice 32. When this predetermined gas pressure is reached, the ball 30will undergo further temporary deformation, momentarily breaking theseal around the peripheral edge portions of the vent orifice 32 andallowing gas to escape from inside the cell in the same manner as justdescribed. The valve will remain open until the forces exerted againstthe ball 30 by the internal gas pressure are less than the sealingforces exerted by the resilient stress of the ball 30 whereupon the ballwill again reseat against the peripheral edge portions of the ventorifice 32 and reseal the valve.

It will be readily seen that the preferred two-mode version of thepressure relief vent valve of the invention offers the advantage in thatthe cell can be maintained in hermetically sealed condition during theperiod of storage and thereby prolongs the storage life of the cell. Itmay be noted that during use or discharge of the cell, the internal gaspressure which can develop inside the cell usually builds up quiterapidly and it is most advantageous to vent the gas as soon as possibleat fairly low venting pressures. During the period of storage, however,any internal gas pressure which may develop builds up at a slower rateand frequent gas venting at low pressures is not required. Venting atfrequent intervals may in fact be detrimental since such venting may beaccompanied by loss of moisture or water vapor which could result indrying out of the cell. With the preferred two-mode version of thepressure relief vent valve of the invention, the valve will not open tovent gas during the period of storage at the relatively low ventingpressures for which the valve is operable to vent gas during dischargeof the cell and will remain closed until an abnormally high internal gaspressure is reached which should be relieved in order to prevent thepossibility of cell explosion.

FIG. 3 shows a different embodiment of the invention wherein thetwo-mode" version of the pressure relief vent valve is incorporatedwithin the cell closure at the bottom of the cell. The resilient ball 34is force-fitted or pressed into a fairly deep circular vent orifice 35provided within the terminal rivet 22. The rivet head portion of theterminal rivet 22 is formed with an enlarged circular recess 36 forreceiving the resilient ball 34 when it is expelled from within the ventorifice 35. A disc-shaped spring member 38 is positioned in contactagainst the rivet head and overlies the circular recess 36 being biasedinto resilient contact at its outer peripheral edges against a metallicbottom cover plate 40 provided with a vent hole 41. The depth of thecircular recess 36 is such that the resilient ball 34 when expelled fromthe vent orifice 35 is maintained by the spring member 38 in a flattenedconfiguration overlying the vent orifice 35 as shown in phantom lines inFIG. 3 and forming a normally fluid-tight seal around the peripheraledge portions of the vent orifice 35. The spring member 38 in thisembodiment acts both as a retainer means for the resilient flattenedball 34 upon being expelled from the vent orifice 35 and as a means formaintaining electrical contact between the terminal rivet 22 and themetallic bottom cover plate 40 serving as the negative terminal of thecell.

In the embodiment of the invention illustrated in FIG. 4, the pressurerelief vent valve is incorporated within a modified cell closure whichis similar to that used in the cell previously described, except thatelectrical connection with the metallic bottom cover plate 40 isachieved by means of a polarized metallic cap 42. The metallic cap 42 isprovided with a central protuberance 43 which makes contact with adisc-shaped spring member 44, the outer peripheral edges of which arebiased into resilient contact with the metallic bottom cover plate 40.The cap 42 underlies the polarized rigid metallic cover 45 which is incontact with the anode current collector 46. The metallic cover 45together with the cap 42 reside within a generally U-shaped annular sealgasket 47 which is radially compressed between the metallic cover 45 andthe lower peripheral edges of the container 10.

The pressure relief vent valve used in this embodiment of the inventionincludes a resilient ball 48 positioned within the central protuberance43 on the metallic cap 42 and overlies a shallow vent orifice 49provided within the metallic cover 45. The protuberance 43 serves as aretainer means for maintaining the resilient ball 48 in place over thevent orifice 49 and for compressing and deforming the ball 48 into aflattened configuration forming a normally fluid-tight seal around theperipheral edge portions of the vent orifice 49. It should be noted thatin this embodiment of the invention the pressure relief vent valve isoperable to vent gas from inside the cell at relatively low ventingpressures and does not incorporate the so-called two mode" version ofthe valve as illustrated in FIGS. 1-3.

FIG. 5 illustrates another embodiment of the invention which is usefulfor incorporating the pressure relief vent valve into a miniature sizecell. The cell comprises a metallic container 50 having its upper openend sealed by a generally L- shaped annular seal gasket 51 suitably of arelatively hard insulating plastic material. A polarized metallic cover52 resides within the L-shaped annular seal gasket 51 and is formed witha downwardly depending central stem portion 53 which fits through theopening in the seal gasket 51. An electrical conductor member 54 such asa metallic pin is welded or otherwise secured to the central sternportion 53 and makes electrical connection with one of the electrodes ofthe cell. A metallic terminal cap 55 provided with a vent hole 56 ispositioned over the metallic cover 52 and has its lower peripheral edgeslocked in place by a peripheral bead or flange 57 formed around theouter peripheral edges of the metallic cover 52. The seal gasket 51 isradially compressed between the metallic cover 52 and the container andthe upper peripheral edges of the container 10 are crimped over a sealring 58 suitably of a relatively soft resilient plastic material.

The two-mode version of the pressure relief vent valve of thisembodiment includes a resilient ball 60 which is forcefitted or pressedinto a deep vent orifice 62 provided within the central stem portion 53.As in the case of the previously described embodiments of the ventvalve, the resilient ball 60 is compressed and deformed into anelongated or cylindrospherical configuration when force-fitted orpressed into the vent orifice 62 forming a high pressure seal. The spaceor gap between the metallic terminal cap 55 and the peripheral edgeportions of the vent orifice 62 is such that the ball 60 is maintainedin a flattened configuration as shown in phantom lines in FIG. 5 whenthe ball is expelled from within the vent orifice 62.

The embodiment of the invention illustrated in FIG. 6 is basically thesame as that just described, except that the vent orifice 62 is formedwith a conical shaped valve seat around its peripheral edge portions asindicated at 63. Thus, the resilient ball 60 when expelled from the ventorifice 62 is retained by the metallic terminal cap 55 in a flattenedconical configuration against the conical surfaces 63 around the openingof the vent orifice 62 forming the valve seat. It will be seen that inthis embodiment of the invention, the resilient ball 60 is compressed toa degree which is somewhat less than when the ball is deformed to aflattened configuration as in the previous embodiments described andthat, therefore, the vent valve is capable of venting gas atsubstantially lower internal gas pressures from inside the cell. It willalso be noted in this embodiment that the cell is of the same basicconstruction as that illustrated in FIG. 5 except that the upperperipheral edges of the container 10 are crimped over the upper edges ofan L- shaped annular seal gasket 64.

FIG. 7 illustrates still another embodiment of the inventionincorporating the two-mode" version of the pressure relief vent valvewhich can be used in the same type of cell construction as thatillustrated in FIGS. 3 and 4. The cell includes an inverted polarizedmetallic cup container 65 provided with an outer metallic jacket 66separated from the container 65 by an insulating liner 67 suitably ofpaper or other fibrous material. The open end of the container 65 issealed by a rigid annular insulating cover 68 suitably of a relativelyhard plastic material. The peripheral edge portion of the annularinsulating cover 68 abuts against the side walls of the container 65which are radially compressed inwardly to provide a fluid-tight sealjuncture between the cover 68 and the container 65. The lower peripheraledges of the container 65 are crimped over a peripheral bead or flange69 formed integrally around the outer edges of the insulating cover 68.The metallic jacket 66 and the insulating liner 67 extend beyond thelower extremities of the container 65 and are similarly crimped over theouter edges of a metallic bottom cover plate 70 which serves as thenegative terminal of the cell.

The pressure relief vent valve used in this embodiment of the inventionincludes an inverted metallic cup 71 which resides within a shallowcircular recess 72 formed within the annular insulating cover 68. Thecup 71 is provided with a central upwardly extending cylindrical stem orsleeve portion 73 which is fluid-tightly fitted through the opening inthe insulating cover 68 and provides a fairly deep elongated ventorifice for the valve. A resilient ball 74 is force-fitted or pressedinto the elongated stem or sleeve portion 73 and is compressed anddeformed into an elongated configuration as shown, sealing off the ventorifice under a high sealing pressure in the same manner as previouslydescribed. Positioned inside the metallic cup 71 is a vent washer 75having its opening 76 located in alignment with the opening of thecentral stem or sleeve portion 73. In this embodiment of the invention,the opening 76 in the vent washer 75 may be used as a means forincreasing the initial first mode venting pressure at which theresilient ball 74 will be expelled from the vent orifice. Thus, theopening 76 in the vent washer 75 may be made of a size slightly smallerin diameter than the internal diameter of the central stem or sleeveportion 73 so as to restrict the outward movement of the resilient ball74 upon the build-up of an abnormally high internal gas pressure insidethe cell.

Once the resilient ball 74 has been expelled from within the ventorifice and through the opening 76 in the vent washer 75 the ball 74 ismaintained in position overlying the opening 76 and is compressed anddeformed into a flattened configuration as shown in phantom lines inFIG. 7 by means of a metallic cap 77. The cap 77 is held tightly inplace by the lower peripheral edges of the inverted metallic cup 71which are crimped over the outer edges of the cap 77. A conductor member78 is secured as by welding to the stem or sleeve portion 73 of themetallic cup 71 and makes electrical connection with one electrode ofthe cell. A resilient spring member 79 which may be punched out from thecap 77 is positioned in contact with the metallic bottom cover plate 70which serves as the negative terminal of the cell.

An important feature of the pressure relief .vent valve of the inventionis that the valve is resealable once the internal gas pressure whichdevelops inside the cell has been relieved. Thus, it will be seen thatin all of the embodiments of the vent valve described the resilientflattened ball of elastomeric material possesses an inherent resilientstress which acts as a biasing force to restore the ball back into itssealing position against the peripheral edge portions of the ventorifice when the ball is caused to undergo further temporary deformationupon the build-up of a predetermined internal gas pressure inside thecell. It should be noted, however, that in the case of miniature sizecells such as AAA cells, the primary function of the valve is to act asa positive fail-safe pressure relief vent and once the ball has beenexpelled from the vent orifice, the valve must not plug up and fail tovent. In order to insure that the vent valve will operate safely inthese miniature size cells, it may be desirable to assemble the ventvalve in such a way that the resilient ball is under a fairly low finalcompression and, therefore, will vent at relatively low ventingpressures. In such instances, the resilient ball may be prevented fromseating properly with the vent orifice to achieve resealability due tothe presence of particles of active material which may be carried uponto the valve seat from inside the cell. The failure of the valve toseal or reseat properly is not viewed as a fault of the valve but ratheras simply a result of the environment.

In the broadest aspect of the invention, the resilient ball used in thepressure relief vent valve may be made from most any resilientelastomeric material. Preferably, however, in the case of an alkalinegalvanic cell, the resilient ball should be made from a resilientelastomeric material which is chemically resistant to the alkalineelectrolyte of the cell. A suitable chemically resistant elastomericmaterial for the resilient ball is an ethylene-propylene copolymer. Thehardness of the resilient ball preferably is in the range of from about60 to 70 Durometer and the ball should be capable of maintaining itsresiliency over a long period of time under a substantial amount ofdeformation; for example, in the first mode of operation of the valve,the diameter of the elongated or cylindro-spherical ball force-fitted orpressed into the vent orifice should be about 50 to 70 percent of thediameter of the ball in its initial spherical shape.

As already indicated, the peripheral edge portions surrounding theopening of the vent orifice may be used to form the valve seat for theresilient ball in the pressure relief vent valve of the invention. Itshould be understood, however, that the valve seat for the resilientball may be formed by a separate member overlying the opening of thevent orifice as in the case of the vent washer used in the embodimentillustrated in FIG. 7. Generally speaking, the valve seat in all theembodiments except that illustrated in FIG. 6, should be roughly 90degrees in crosssection forming a square shoulder with a sharp edge forminimal contact with the resilient ball to insure a fluid tight seal.

it should be noted that the resilient ball used in the pressure reliefvent valve is of an initial spherical shape and that the valve seatagainst which the ball bears is circular in the case where the valve isused only as a low pressure vent as illustrated in FIG. 4 or in the caseof the two-mode version of the valve. However, when the valve is usedonly in the first mode of operation as a positive fail safe pressurevent as described above in connection with miniature size cells, theresilient ball may be ofother configurations such as cylindrical orspheroid, for example, although a spherical ball is preferred.

In some cases, it may be desirable to use a surface additive forlubricating the resilient ball in order to facilitate pressing the ballinto the vent orifice and to insure that the ball is properly expelledfrom the vent orifice in the two-mode version of the valve. Thelubricant also serves to seal minor imperfections in the valve seat orsurfaces of the ball and prevents salt encrustment from any liquidelectrolyte which may come into contact with the vent valve, Suitablesurface additives and lubricants include silicone grease, soap andwaxes, for example.

As an illustration of the practice of the invention, a number ofalkaline zinc-manganese dioxide cells of various sizes, e.g., D, AA, AAAcells, have been made using the pressure relief vent valve of theinvention. The resilient deformable ball used in the valves was ofspherical shape and was made from an ethylene-propylene copolymer. Thediameter of the balls ranged from about three thirty-seconds tothree-sixteenths inch depending on the size of the cell. The ventingpressure level of the vent valves used in these cells was set bysuitable choice of parameters, i.e., resiliency of the ball, thedifference in relative sizes between the ball and the vent orifice,etc., over a wide range of sealing pressures from about 5 to 500 psi.The pressure relief vent valves were found to perform satisfactorily inthat gas venting occurred in a predictable and reproducible manner forthe various venting pressures used.

It will be seen then that the present invention provides a novel andimproved pressure relief vent valve for relieving high internal gaspressures from inside a fluid-tight sealed container and especially asealed alkaline galvanic cell. The pressure relief vent valve of theinvention is particularly advantageous in that it is simple and compactand readily adaptable to use in miniature size cells, employs a minimumnumber of parts with the resilient ball being the only moving part, canbe assembled as a unit with little or no handling and employs no partshaving critical tolerances in its assembly. The vent valve isfurthermore resealable once the internal gas pressure has been relievedfrom the inside of the container and is responsive over a wide range ofgas pressures and is relatively inexpensive to manufacture.

What is claimed is:

1. In a galvanic cell including a fluid-tight sealed container; apressure relief vent valve for releasing gas from inside said container,said valve comprising, in combination, a resilient deformable ball of anelastomeric material positioned to overlie a vent orifice provided in aportion of said container and to contact a valve seat provided aroundthe peripheral edge portions of said vent orifice, said ball being of aninitial spherical shape and of a size larger than that of said ventorifice, and a retainer means positioned over and spaced from said valveseat such that the gap between said retainer means and said valve seatis smaller than the size of said resilient ball whereby said ball ismaintained in a state of compression between said retainer means andsaid valve seat and is distorted into a flattened configuration, saidflattened ball exerting a resilient sealing force against said valveseat forming a normally fluidtight seal between said ball and said valveseat, said flattened ball being capable of undergoing further temporarydeformation upon the build-up of a predetermined high internal gaspressure inside said container momentarily breaking the seal andallowing gas to escape through said vent orifice.

2. The galvanic cell in accordance with claim 1 wherein the resilientdeformable ball is made of an elastomeric material possessing a hardnessof from about 60 to Durometer.

3. The galvanic cell in accordance with claim 1 wherein the valve seatis formed with a substantially square shoulder providing a sharpperipheral edge for minimal contact with said resilient ball.

4. The galvanic cell in accordance with claim 1 wherein the surfaces ofthe valve seat are of a substantially conical configuration.

5. The galvanic cell in accordance with claim 1 wherein the valve seatis formed by the inner peripheral edge portions of said vent orifice.

6. The galvanic cell in accordance with claim 1 wherein one end of saidcontainer is sealed by a closure comprising a rigid metallic cover whichfits in said end of said container and a seal gasket fluid-tightlysealed between said metallic cover and said container, and wherein thevent orifice is provided within said metallic cover.

7. The galvanic cell in accordance with claim 6 wherein the retainermeans is a metallic cap having a protuberance which fits over saidresilient ball in pressure contact therewith and further including aspring member in electrical contact between said protuberance and ametallic bottom cover plate locked in engagement around the extremitiesof said cell.

8. In a galvanic cell including a fluid-tight sealed container; apressure relief vent valve for releasing gas from inside said container,said valve comprising a resilient deformable ball of an elastomericmaterial force-fitted into a smaller size vent orifice provided within aportion of said container, said ball being compressed and deformed intoa substantially elongated configuration within said vent orifice suchthat the resilient stress of said ball exerts a high sealing forceagainst the side walls of said orifice, said ball being expelled fromsaid vent orifice upon the build-up of an abnormally high internal gaspressure inside said cell.

9. The galvanic cell in accordance with claim 8 further including avalve seat provided around the peripheral edge portions of said ventorifice and a retainer means positioned over and spaced from said valveseat such that the gap between said retainer means and said valve seatis smaller than the size of the resilient ball in its initial shapeprior to being force-fitted into said vent orifice, said ball uponexpulsion from said vent orifice being compressed and deformed by saidretainer means into a substantially flattened configuration overlyingsaid vent orifice and in contact with said valve seat forming afluid-tight seal between said ball and said valve seat.

10. The galvanic cell in accordance with claim 9 wherein the ventorifice is provided within the closed end wall of said container andwherein the retainer means comprises a metallic cover plate having acentral protuberance positioned over said closed end wall of saidcontainer and spaced from said valve seat, the gap between said valveseat and said central protuberance being smaller than the size of saidresilient ball in its initial shape prior to being force-fitted intosaid vent orifice.

11. The galvanic cell in accordance with claim 9 wherein one end of saidcontainer is sealed by a closure comprising a rigid metallic cover whichfits in said end of said container and an annular seal gasketfluid-tightly sealed between said metallic cover and said container,said metallic cover being formed with a centrally located depending stemportion which fits through the opening in said seal gasket, and whereinthe vent orifice is provided through said centrally located dependingstern portion of said metallic cover.

12. The galvanic cell in accordance with claim 11 wherein the retainermeans comprises a metallic terminal cap positioned over and secured tosaid metallic cover, said terminal cap being spaced from the valve seatformed around the peripheral edge portions of said vent orifice suchthat the gap between said terminal cap and said valve seat is smallerthan the size of the resilient ball in its initial shape prior to beingforce-fitted into said vent orifice.

13. The galvanic cell in accordance with claim 12 wherein the surfacesof the valve seat are of a substantially conical configuration.

14. The galvanic cell in accordance with claim 9 wherein one end of saidcontainer is sealed by a closure comprising a generally U-shaped annularseal gasket which fits in said end of said container, a rigid metalliccover positioned within said U-shaped seal gasket and a terminal rivetfitted through the central opening of said seal gasket, said seal gasketbeing fluidtightly sealed between said metallic cover and said rivet andbetween said metallic cover and said container, and wherein the ventorifice is provided through said terminal rivet.

15. The galvanic cell in accordance with claim 14 wherein the rivet headportion of said terminal rivet is formed with a circular recesscommunicating with said vent orifice, the depth of said circular recessbeing smaller than the size of the resilient ball in itsinitial shapeprior to being force-fitted into said vent orifice, and wherein saidretainer means comprises a resilient spring member overlying saidcircular recess and making electrical contact with a metallic coverplate locked in engagement around the outer extremities of the cell.

16. The galvanic cell in accordance with claim 9 wherein one end of thecontainer is sealed by a closure comprising a rigid insulating annularcover which fits in said end of said container, the outer peripheraledges of said insulating annular cover abutting with the peripheraledges of said container forming a fluid-tight seal, said insulatingannular cover having a shallow recess formed therein to accommodate ametallic cup having a centrally located depending stem portion fittingthrough the opening in said insulating annular cover, said dependingstem portion forming the vent orifice and wherein a vent washer ispositioned within said metallic cup having its opening in alignment withthe opening of the depending stem portion and forming the valve seat.

17. The galvanic cell in accordance with claim 16 wherein the retainermeans comprises a metallic cap positioned over said resilient ball inpressure contact therewith, said cap being spaced from the valve seatformed by the opening in said vent washer such the gap between saidmetallic cup and said valve seat is smaller than the size of theresilient ball in its initial shape prior to being force-fitted intosaid vent orifice.

18. The galvanic cell in accordance with claim 17 wherein a resilientspring member is positioned in contact between said metallic cap and ametallic closure plate locked in engagement around the outer extremitiesof said cell.

19. The galvanic cell in accordance with claim 17 wherein the opening insaid vent washer is of a smaller size than the vent orifice formed bythe centrally located depending stem portion of said metallic cup.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,664,878 Dated May 23, 1972 Inventor(s) H. K. Amthor It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 3, lines 2 and 3 (Page 6, lines 17 and 18 of Application No.853,279

"J.L.S. Daley on February 15, 1960" should read R. Carmichael et al'. onJuly 3, 1962 Column 3, line 23 (page 7, line 5 of Application No.

the numeral "12" should read ll Column 5, lines 36, 37 and 69 (page 11,lines 30 and 31, and

page 12, line 30 of Application No. 853,279):

the numeral "10" should read 50 Signed and Scaled this twenty-eight OfOctober 1 975 [SEAL] A ttes t:

RUTH C. MASON C. MARSHALL DANN Arresting 0mm Commissioner of Patents andTrademarks

1. In a galvanic cell including a fluid-tight sealed container; apressure relief vent valve for releasing gas from inside said container,said valve comprising, in combination, a resilient deformable ball of anelastomeric material positioned to overlie a vent orifice provided in aportion of said container and to contact a valve seat provided aroundthe peripheral edge portions of said vent orifice, said ball being of aninitial spherical shape and of a size larger than that of said ventorifice, and a retainer means positioned over and spaced from said valveseat such that the gap between said retainer means and said valve seatis smaller than the size of said resilient ball whereby said ball ismaintained in a state of compression between said retainer means andsaid valve seat and is distorted into a flattened configuration, saidflattened ball exerting a resilient sealing force against said valveseat forming a normally fluid-tight seal between said ball and saidvalve seat, said flattened ball being capable of undergoing furthertemporary deformation upon the build-up of a predetermined high internalgas pressure inside said container momentarily breaking the seal andallowing gas to escape through said vent orifice.
 2. The galvanic cellin accordance with claim 1 wherein the resilient deformable ball is madeof an elastomeric material possessing a hardness of from about 60 to 70Durometer.
 3. The galvanic cell in accordance with claim 1 wherein thevalve seat is formed with a substantially square shoulder providing asharp peripheral edge for minimal contact with said resilient ball. 4.The galvanic cell in accordance with claim 1 wherein the surfaces of thevalve seat are of a substantially conical configuration.
 5. The galvaniccell in accordance with claim 1 wherein the valve seat is formed by theinner peripheral edge portions of said vent orifice.
 6. The galvaniccell in accordance with claim 1 wherein one end of said container issealed by a closure comprising a rigid metallic cover which fits in saidend of said container and a seal gasket fluid-tightly sealed betweensaid metallic cover and said container, and wherein the vent orifice isprovided within said metallic cover.
 7. The galvanic cell in accordancewith claim 6 wherein the retainer means is a metallic cap having aprotuberance which fits over said resilient ball in pressure contacttherewith and further including a spring member in electrical contactbetween said protuberance and a metallic bottom cover plate locked inengagement around the extremities of said cell.
 8. In a galvanic cellincluding a fluid-tight sealed container; a pressure relief vent valvefor releasing gas from inside said container, said valve comprising aresilient deformable ball of an elastomeric material force-fitted into asmaller size vent orifice provided within a portion of said container,said ball being compressed and deformed into a substantially elongatedconfiguration within said vent orifice such that the resilient stress ofsaid ball exerts a high sealing force against the side walls of saidorifice, said ball being expelled from said vent orifice upon thebuild-up of an abnormally high internal gas pressure inside said cell.9. The galvanic cell in accordance with claim 8 further including avalve seat provided around the peripheral edge portions of said ventorifice and a retainer means positioned over and spaced from said valveseat such that the gap between said retainer means and said valve seatis smaller than the size of the resilient ball in its initial shapeprioR to being force-fitted into said vent orifice, said ball uponexpulsion from said vent orifice being compressed and deformed by saidretainer means into a substantially flattened configuration overlyingsaid vent orifice and in contact with said valve seat forming afluid-tight seal between said ball and said valve seat.
 10. The galvaniccell in accordance with claim 9 wherein the vent orifice is providedwithin the closed end wall of said container and wherein the retainermeans comprises a metallic cover plate having a central protuberancepositioned over said closed end wall of said container and spaced fromsaid valve seat, the gap between said valve seat and said centralprotuberance being smaller than the size of said resilient ball in itsinitial shape prior to being force-fitted into said vent orifice. 11.The galvanic cell in accordance with claim 9 wherein one end of saidcontainer is sealed by a closure comprising a rigid metallic cover whichfits in said end of said container and an annular seal gasketfluid-tightly sealed between said metallic cover and said container,said metallic cover being formed with a centrally located depending stemportion which fits through the opening in said seal gasket, and whereinthe vent orifice is provided through said centrally located dependingstem portion of said metallic cover.
 12. The galvanic cell in accordancewith claim 11 wherein the retainer means comprises a metallic terminalcap positioned over and secured to said metallic cover, said terminalcap being spaced from the valve seat formed around the peripheral edgeportions of said vent orifice such that the gap between said terminalcap and said valve seat is smaller than the size of the resilient ballin its initial shape prior to being force-fitted into said vent orifice.13. The galvanic cell in accordance with claim 12 wherein the surfacesof the valve seat are of a substantially conical configuration.
 14. Thegalvanic cell in accordance with claim 9 wherein one end of saidcontainer is sealed by a closure comprising a generally U-shaped annularseal gasket which fits in said end of said container, a rigid metalliccover positioned within said U-shaped seal gasket and a terminal rivetfitted through the central opening of said seal gasket, said seal gasketbeing fluid-tightly sealed between said metallic cover and said rivetand between said metallic cover and said container, and wherein the ventorifice is provided through said terminal rivet.
 15. The galvanic cellin accordance with claim 14 wherein the rivet head portion of saidterminal rivet is formed with a circular recess communicating with saidvent orifice, the depth of said circular recess being smaller than thesize of the resilient ball in its initial shape prior to beingforce-fitted into said vent orifice, and wherein said retainer meanscomprises a resilient spring member overlying said circular recess andmaking electrical contact with a metallic cover plate locked inengagement around the outer extremities of the cell.
 16. The galvaniccell in accordance with claim 9 wherein one end of the container issealed by a closure comprising a rigid insulating annular cover whichfits in said end of said container, the outer peripheral edges of saidinsulating annular cover abutting with the peripheral edges of saidcontainer forming a fluid-tight seal, said insulating annular coverhaving a shallow recess formed therein to accommodate a metallic cuphaving a centrally located depending stem portion fitting through theopening in said insulating annular cover, said depending stem portionforming the vent orifice and wherein a vent washer is positioned withinsaid metallic cup having its opening in alignment with the opening ofthe depending stem portion and forming the valve seat.
 17. The galvaniccell in accordance with claim 16 wherein the retainer means comprises ametallic cap positioned over said resilient ball in pressure contacttherewith, said cap being spaced from the valve Seat formed by theopening in said vent washer such the gap between said metallic cup andsaid valve seat is smaller than the size of the resilient ball in itsinitial shape prior to being force-fitted into said vent orifice. 18.The galvanic cell in accordance with claim 17 wherein a resilient springmember is positioned in contact between said metallic cap and a metallicclosure plate locked in engagement around the outer extremities of saidcell.
 19. The galvanic cell in accordance with claim 17 wherein theopening in said vent washer is of a smaller size than the vent orificeformed by the centrally located depending stem portion of said metalliccup.